The Buoyant founders, William Morgan and Oliver Gould, created Linkerd. William Morgan is credited for coining the term service mesh, which is now used by all major providers. 

Linkerd, which comes from the RPC system called Finagle, was developed by Twitter to handle its extremely high volume. Linkerd 1.x turned Finagle into the first service mesh. The Conduit (https://conduit.io) project arose out of the desire to build a much simpler system to solve the same issues Linkerd 1.x was solving. Eventually, it was decided to rebrand Conduit as Linkerd 2.0, which is an open source service mesh for cloud-native applications. Linkerd 2.x is a graduated project from CNCF (https://cncf.io), and it only runs in a Kubernetes environment. 

This book will only cover Linkerd 2.x, which is a service mesh for Kubernetes, and it provides runtime debugging, observability, reliability, and security for running services. Linkerd 2.x has a centralized control plane similar to Istio. This open source project is available at https://linkerd.io. Linkerd 1.x is a different service mesh compared to Linkerd 2.x. It runs on Kubernetes, AWS ECS, DC/OS, Docker, and locally. Linkerd uses its own sidecar, whereas all of the other service mesh providers use the Envoy sidecar proxy.